1. Field of the Invention
This invention relates to a method of and apparatus for effecting variable speed replay of digital audio, with constant output sampling rate.
2. Prior Art
The design of conventional analogue audio recorders permits replay over a wide range of tape speeds. This is a particular useful feature exploited by sound editors for monitoring the tape at spooling speeds, or accurate location by `rock and roll` at very low tape speeds, that is to say moving the tape backwards and forwards to home in on the desired location. No attempt is made to equalise the replay process because adequate intelligibility can be achieved without it and the low quality does not affect the final product. Tape speed varies from zero to up to 5 times normal speed. In contrast it is also customary to provide variable speed replay over a small range (.+-.10%) to achieve deliberate pitch change, develop special effects such as flanging, or enable synchronisation with other machines. For these cases, the highest quality must be maintained since the speed change is part of the final product.